The overall goal of this R15 Academic Research Enhancement Award (AREA) proposal is to implement and validate a new three-dimensional (3-D) motion tracking system within an athletic pre-participation physical exam (PPE). Injuries to the anterior cruciate ligament (ACL) have reached epidemic proportions among young female athletes, with a high physical and financial cost. Research efforts toward reducing ACL injury have focused on anatomical, hormonal, and neuromuscular factors that may contribute to increased risk. The factor that appears to show the greatest promise to discriminate athletes at risk is 3-D motion analysis of lower extremity dynamics during athletic activities. To be clinically useful, 3-D motion analysis must be accessible to large numbers of athletes. A 3-D motion analysis screening tool for ACL injury risk that can be deployed on a large scale is needed. Such a tool must be able to record outside of the laboratory with a single camera, require little or no calibration and little technical expertise for the user. Further, such a system should generate nearly instantaneous feedback to the clinician and athlete, and must be relatively inexpensive. No technology currently exists on the market that can remotely meet these criteria. The Retro-Grate Reflector (RGR) is a novel single-camera 3-D motion tracking technology. The RGR exploits the information content of moiri patterns generated by a lightweight, multi-layer passive optical target to determine 3-D information with a single camera. The specific aims of this study are to implement RGR motion tracking in the PPE for intercollegiate athletes and validate the results against a high-precision Eagle motion analysis system. The screening device will be utilized during the PPE screening of athletes participating in intercollegiate men's and women's soccer and basketball and women's volleyball at UW-Milwaukee. The athletes will perform slow squatting, drop jumping, and side cutting maneuvers while 3-D motion data are collected with the RGR system. These athletes will later attend a testing session where the protocol will be repeated with the Eagle system. Results from the Eagle system will serve as a standard for comparison with the RGR data. The long-term goal is to establish clinically valid thresholds for injury screenings, and this device will allow for large-scale collection of 3-D motion data within a typical PPE. In order to achieve this goal in a future R01 submission, the efficacy of use of the RGR motion capture system within a PPE must first be established, and its results validated against standard 3-D motion capture techniques. Other investigators have demonstrated effective identification of the at risk population by motion analysis and 75% reduction in injury risk with targeted training. If motion analysis could be included in the PPE, the potential exists to reduce the number of traumatic knee injuries by 15,000 per year. PUBLIC HEALTH RELEVANCE. Anterior cruciate ligament injuries are far too common for young athletes, particularly females. While they can be surgically repaired (at great cost), long-term consequences persist. The results of this study will establish a new way to identify athletes who are at greatest risk, allowing for targeted interventions and a dramatic decrease in the rate of these injuries. [unreadable] [unreadable]